| The health of watershed ecosystem is an important part of the high-quality development of watershed.It is of great significance to carry out comprehensive evaluation of watershed ecosystem health and explore the space-time evolution law and dynamic simulation of watershed ecosystem health for the spatial integration protection of river basin and the coordinated management of environment.The report to the 20th National Congress of the Communist Party of China pointed out that water resources,water environment and water ecological management should be coordinated to promote the ecological protection and management of important rivers,lakes and reservoirs[1].In2023,the State put forward the Opinions on Strengthening the Work of Soil and Water Conservation in the New Era,which pointed out that comprehensive treatment of small watersheds should be comprehensively promoted to improve quality and efficiency,and the production and living ecology should be coordinated,and comprehensive treatment of small watersheds should be comprehensively carried out in key areas.Here,how to define the scope of important rivers,lakes,reservoirs and key areas,the first consideration is the health problem of the river basin.Under the premise of health diagnosis,purposeful comprehensive basin management will be conducive to the establishment of relevant national policies and measures.Jiangxi Province,which possessed the only complete and unique geographical unit of the Great Lakes Basin in China,undertakes the important task of exploring the institutional innovation of ecological civilization such as integrated watershed management.As one of the main rivers in the Poyang Lake system of the Yangtze Watershed,the Fuhe Watershed carries a number of famous historical and cultural celebrities such as Tang Xianzu,Wang Anshi,Zeng Gong,and has rich cultural and ecological tourism resources.Similarly,it is also an important area for the construction of the old revolutionary base and the Party.It is a demonstration area for the construction of the National Ecological Civilization Pilot Zone（Jiangxi）to explore the comprehensive management system of the watershed and innovate the comprehensive management model of the watershed,the first batch of pilot areas for the comprehensive treatment and sustainable development of the watershed water environment,and the pilot area for exploring the realization of the"green water and green mountains are golden mountains and silver mountains"and the national ecological product value realization mechanism.Taking the Fuhe Watershed as an example,exploring the issue of ecosystem health assessment in the basin will provide decision-making basis for the comprehensive management of the national exploration basin,the planning,management and protection of the Jiangxi exploration basin,and the comprehensive management of the basin.At the same time,it provides an important and effective way and reference for establishing the model and method of watershed ecosystem health assessment.Guided by management science and its system science theory,this study selects the Fuhe Watershed（Fuzhou section）as the research area,takes 11 counties and districts of the Fuhe Watershed in Fuzhou City and the upper,middle and lower reaches of the basin as the evaluation units,takes the relevant historical data from 2010 to 2020 as the basis,starts from the interaction between human activities and natural ecology,and takes the natural condition restriction,ecological health indication and human activity impact subsystem structure of the basin as the main line,The conceptual model of DPRIRM framework for watershed ecosystem health assessment was constructed,and the diagnostic assessment of health,the temporal and spatial evolution rules and dynamic simulation were studied.The main research contents include:（1）It has built a conceptual model of watershed ecosystem health assessment framework.Considering the natural conditions of the basin and the impact of human activities on the health of the basin,through the analysis of impact factors and driving forces,the stress factors were identified,and the DPRIRM framework conceptual model of the basin ecosystem health assessment was constructed;（2）It has conducted a research on diagnostic assessment method of watershed ecosystem health based on cloud model.With the help of the research paradigm of system theory,a diagnostic evaluation index system of watershed ecosystem health is constructed from the whole watershed.Based on the characteristics of typical watersheds and the uncertainty of weight information,the standard evaluation cloud is established through the standard interval segmented data of the evaluation index,the subjective and objective combination weighting of grey correlation degree,and the comprehensive similarity calculation between the comprehensive evaluation cloud of the object to be evaluated and the standard evaluation cloud,A comprehensive evaluation method of cloud model based on grey correlation degree and combination weighting of information cloud and taking shape and distance into account is constructed;（3）It has done a research on watershed ecosystem health simulation and scenario analysis based on SD model.Through the analysis of the interrelationship and feedback loop between the constituent elements of each subsystem of watershed ecosystem health,the flow level,flow rate and auxiliary variables within each subsystem are set,the flow level and flow rate sub-structure is established,the basic input tree model and variable equation of the flow rate of watershed ecosystem health are established,and the stock flow chart of watershed ecosystem health is constructed by introducing embedded operation,The number and order of the branch vector feedback loop contained in the feedback set of the complex system are determined by calculating the branch vector determinant of the input tree model and analyzing the feedback loop;（4）It has analyzed the health problems of the ecosystem in the Fuhe Watershed empirically.Taking the administrative region（county）and upper,middle and lower reaches of the Fuhe Watershed as the evaluation units,a multi-source database for problem research is formed through multi-technical means.Using cloud model,system dynamics and other technical methods,this paper makes an empirical analysis on the evolution process,current situation,optimal regulation and spatial management of watershed health,and puts forward corresponding policy recommendations on the analysis results.The results showed that:（1）there was a"many to many"correspondence between driving forces and stress factors,and there were 62pairs of correlation between 14 driving forces and 18 stress factors;（2）From the perspective of the unit as a whole,the upper,middle and lower units of the Fuhe Watershed are in a"sub-healthy"state.During the three periods of the study,39.4%of the 11 counties and districts were in the"healthy"state,51.5%were in the"sub-healthy"state,and 9.1%were in the"disease"state;（3）From the perspective of spatial distribution,the east-west direction of the Fu Watershed is in good health,the south-north direction is in the"sub-health"state,and the overall along the main stream of the Fu River is in the"sub-health"state,which is consistent with the overall"sub-health"state of the upper,middle and lower reaches of the Fu Watershed;（4）According to the basic tree entry modeling and feedback loop analysis of flow rate,the feedback set among the factors affecting the health of the watershed ecosystem includes15 branch vector feedback loops,of which the minimum is the third-order branch vector feedback loop and the maximum is the ten-order branch vector feedback loop;（5）The simulation of ecosystem health in the Fuhe Watershed shows that the resource endowment presents"two increases and one decrease",the ecological health presents"stable rise",and human activities present"significant impact".（6）The scenario analysis of ecosystem health in the Fuhe Watershed shows that the system health will be in a"sub-healthy"state in the future under the condition of maintaining the current situation,and will be in a"healthy"state in the future under the condition of optimizing the endogenous and exogenous factors,and in the future under the condition of comprehensive measures,it will be in a"very healthy"state in the future.The contributions of this study include:（1）It has built a DPSIRM framework conceptual model for watershed ecosystem health assessment,and provides a framework theoretical basis for the comprehensive diagnostic evaluation and post diagnostic system analysis of watershed ecosystem health.Adopting the methodology of overall layout and systematic planning of watershed environmental governance,based on the integrated protection of watershed space and coordinated governance of environment,with the help of the theoretical framework of"pressure-state-response（PSR）",on the basis of existing literature[2-7],aiming at the fact that the theoretical framework and extension of PSR are difficult to satisfy the integrity,flexibility and other characteristics of complex watershed systems,as well as the causal relationship and sequence of action among system elements,Coupled with driving force analysis and stress factor identification,this thesis constructs a framework conceptual model of"driving force-pressure-state-impact-response-management（DPSIRM）"for watershed ecosystem health assessment under the complex structural model of natural condition restriction-ecological health indicator-human activity impact subsystem.which provides a framework theoretical basis for the comprehensive diagnostic evaluation and post diagnostic system analysis of watershed ecosystem health.（2）It has established a normal cloud comprehensive evaluation model for the diagnostic fuzzy concept and quantitative numerical transformation of watershed ecosystem health,which achieved the disease analysis of the watershed from the internal state of the system.Based on the diagnostic evaluation of watershed ecosystem health,which is fuzzy and dynamic,this thesis uses the cloud model method applicable to the conversion between qualitative concepts and quantitative values,and on the basis of existing literature[8-12],takes the standard interval of system evaluation indicators as the data source,establishes the standard database by segments,and establishes the cloud model standard evaluation cloud through the golden section comprehensive breakpoint.Based on the calculation of grey correlation degree,the subjective and objective combination weighting is carried out,and the comprehensive evaluation cloud of the object to be evaluated is established.Then,the normal cloud comprehensive evaluation model method of the basin ecosystem health diagnostic fuzzy evaluation is constructed by measuring the similarity between the comprehensive cloud and the standard cloud taking into account the shape and distance.This comprehensive evaluation is to determine the relationship between the health status of the watershed ecosystem and endogenous factors,and to conduct symptom analysis for the comprehensive evaluation of the internal state of the system.（3）It has proposed a quantitative analysis method of the complex relationship between the flow rate basic tree modeling and the factors affecting the health of the watershed ecosystem,which determined the etiology from external influencing factors of the system after health diagnosis.Based on the qualitative analysis of the causal feedback of the relationship between the factors affecting the health of the watershed ecosystem,using the frontier flow rate basic tree entry modeling method of system dynamics,and referring to the existing literature[13-15],the flow level,flow rate and auxiliary variables of the health subsystem structure of the watershed ecosystem were set for the first time,the flow level and flow rate system substructure was established,and the flow rate basic tree entry model and variable equation were constructed,The branch vector determinant calculation and feedback loop analysis were carried out for the tree entry model,which quantitatively and comprehensively reflects the complex relationship between the health impact factors of the watershed ecosystem.This system analysis is a etiological diagnosis that determines the relationship between the health status of the watershed ecosystem and exogenous factors after system health diagnosis. |
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